From this hint, you can say
If you have 4 nodes, then split them to 8 nodes. The first four nodes are the innodes and the last ones are the outnodes.
To connect node 1 to node 2, then
connect node 5 to node 2 with the cost, and connect node 6 with node 1 with the cost.

In my code, I initialized adjMax[][] with infinity. The right is to initialize it with 0.

The main thing in this problem is to build the graph correctly. If you split a node, make sure you add two edges between Vin and Vout. The edge Vin - Vout will have the cost specified in the question. The back edge Vout - Vin will have cost 0 initially.

Now for edges between nodes, you will need 2 forward and 2 residual edges (directed)